Amine hardener for epoxy resins

ABSTRACT

Compounds of formula Ia or Ib  
                 
 
     wherein A is an (n+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and n is an integer from 0 to 5,  
     E is an (m+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and m is an integer from 0 to 3,  
     X is —O—, —COO— or —CHR 4 —, with R 4  and R 3  together forming an ethylene group,  
     R 1  and R 2  are, each independently of the other, hydrogen or methyl,  
     R 3  is hydrogen, or R 3  and R 4  together form an ethylene group,  
     and R 5  is a monovalent aliphatic, cycloaliphatic, araliphatic or aromatic radical, are highly reactive curing agents for epoxy resins and yield cured products having improved resistance to chemicals.

[0001] The present invention relates to polymercaptopolyamines, to aprocess for the preparation thereof, to epoxy resin compositionscomprising such polymercaptopolyamines and to the use of thosecompositions.

[0002] U.S. Pat. No. 5,143,999 describes mixtures of polyamines and ofdithiols derived from polyoxyalkylene glycols as hardeners for epoxyresins. The cured products produced therefrom are distinguished by ahigh degree of flexibility and good viscoelastic properties combinedwith good strength and hardness values.

[0003] The problem of the present invention was to provide curing agentsfor epoxy resins which yield cured products having improved resistanceto chemicals.

[0004] It has now been found that certain polymercaptopolyamines arehighly reactive with respect to epoxy resins even at low temperaturesand that the cured products obtained therefrom have both improvedresistance to chemicals and increased resistance to weathering.

[0005] The present invention relates to compounds of formula Ia or Ib,

[0006] wherein A is an (n+1)-valent aliphatic, cycloaliphatic,araliphatic or aromatic radical and n is an integer from 0 to 5,

[0007] E is an (m+1)-valent aliphatic, cycloaliphatic, araliphatic oraromatic radical and m is an integer from 0 to 3,

[0008] X is —O—, —COO— or —CHR₄—, with R₄ and R₃ together forming anethylene group,

[0009] R₁ and R₂ are, each independently of the other, hydrogen ormethyl,

[0010] R₃ is hydrogen, or R₃ and R₄ together form an ethylene group,

[0011] and R₅ is a monovalent aliphatic, cycloaliphatic, araliphatic oraromatic radical.

[0012] In formula Ia, A can, in principle, be any mono- to hexa-valentepoxy radical. Preference is given to bi-, tri- and tetra-valentradicals.

[0013] Examples of aliphatic radicals are ethylene, propylene,tetramethylene, hexamethylene, poly(oxyethylene), poly(oxypropylene),poly(oxytetramethylene), 2-methyl-1,5-pentanediyl,2,2,4-trimethyl-1,6-hexanediyl, 2,4,4-trimethyl-1,6-hexanediyl and theradicals of aliphatic alcohols after removal of the OH groups, forexample the radicals of trimethylolpropane, pentaerythritol anddipentaerythritol.

[0014] Cycloaliphatic radicals are, for example, cyclopentyl,cyclohexyl, 1,3-cyclopentylene, 4-methyl-1,3-cyclopentylene,1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene,4-methyl-1,3-cyclohexylene, 2,5-norbornanediyl, 2,6-norbornanediyl,7,7-dimethyl-2,5-norbornanediyl, 7,7-dimethyl-2,6-norbornanediyl,cyclohexane-1,3-dimethylene, cyclo-hexane-1,4-dimethylene,3-methylene-3,5,5-trimethylcyclohexylene (isophorone),norbornane-2,5-dimethylene, norbornane-2,6-dimethylene,7,7-dimethylnorbornane-2,5-dimethylene and7,7-dimethylnorbornane-2,6-dimethylene and the radicals ofcycloaliphatic alcohols after removal of the OH groups, for example theradicals of hydrogenated bisphenol A and hydrogenated bisphenol F.

[0015] Suitable araliphatic radicals are, for example, benzyl, theradicals of 1,2-, 1,3- and 1,4-bis(hydroxymethyl)benzene, the radicalsof 1,2,3-, 1,2,4-, 1,2,5- and 1,3,5-tris(hydroxymethyl)benzene and theradicals of bis(hydroxymethyl)naphthalene. Examples of aromatic radicalsare phenyl, naphthyl, the radicals of bisphenols, for example bisphenolA, bisphenol F and dihydroxybiphenyl, and the radicals of phenolnovolaks and cresol novolaks.

[0016] Preference is given to compounds of formula Ia wherein X is —O—and A is a bivalent radical of a bisphenol or of a cycloaliphatic diol,the radical of a phenol novolak or cresol novolak, the bi- totetra-valent radical of an isocyanate/polyol adduct or the tri- tohexa-valent radical of a tri- to hexa-functional aliphatic polyol.

[0017] Special preference is given to compounds of formula Ia wherein Xis —O— and A is a bivalent radical of formula

[0018] the radical of a phenol novolak or cresol novolak, a trivalentradical of formula

[0019] or

[0020] or the tetravalent radical of formula

[0021] R₅ in formulae Ia and Ib is preferably C₁-C₂₀alkyl,C₅-C₁₂cycloalkyl, C₆-C₁₀aryl or C₇-C₁₂aralkyl,

[0022] each of which is unsubstituted or substituted by one or moreamino groups, hydroxyl groups,

[0023] C₁-C₈alkoxy groups or halogen atoms.

[0024] Alkyl groups that are suitable as R₅ are, for example, methyl,ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl andthe various isomers of pentyl, hexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl and octadecyl groups.

[0025] Cycloalkyl is preferably C₅-C₈cycloalkyl, especially C₅- orC₆-cycloalkyl. Examples include cyclopentyl, methylcyclopentyl,cyclohexyl, cycloheptyl and cyclooctyl.

[0026] Aralkyl contains preferably from 7 to 12 carbon atoms andespecially from 7 to 10 carbon atoms and may be, for example, benzyl,phenethyl, 3-phenylpropyl, α-methylbenzyl, 4-phenylbutyl andα,α-dimethylbenzyl.

[0027] Aryl groups are, for example, phenyl, tolyl, mesityl, isityl,naphthyl and anthryl.

[0028] Preference is given to compounds of formulae Ia and Ib wherein R₅is C₂-C₁₀alkyl, C₂-C₁₀aminoalkyl, phenyl, benzyl, cyclohexyl or aradical of formula H₂N—Z—CH₂—NH—, wherein Z is a bivalentcycloaliphatic, araliphatic or aromatic radical or a radical of formula

—(CH₂CH₂NH)_(k)—CH₂—, wherein k is 2 or 3.

[0029] Suitable radicals Z are, for example, the bivalent radicalsmentioned for A hereinbefore.

[0030] Special preference is given to compounds of formulae Ia and Ibwherein R₁ is n-butyl, n-octyl, cyclohexyl, benzyl, 2-aminoethyl,4-(aminomethyl)pentyl, 5-amino-2-methylpentyl, 3-dimethylaminopropyl,3-methylaminopropyl, 4-aminocyclohexyl or a radical of formula

[0031] Preference is given also to compounds of formula Ia or Ib whereinX is O— and R₁ and R₃ are hydrogen.

[0032] The compounds of formula Ia can be prepared in accordance withknown methods from the epoxy compounds of formula IIa:

[0033] wherein A, X, R₁, R₃ and n are as defined hereinbefore.

[0034] In such methods, the epoxy compound of formula IIa is, in a firstreaction step, converted by reaction with thiourea or an alkali-metal orammonium thiocyanate, preferably potassium thiocyanate, into theepisulfide of formula IIIa

[0035] the thiourea or thiocyanate advantageously being used in anamount such that there are from 0.8 to 1.2 equivalents of sulfur for oneepoxy equivalent.

[0036] The reaction can be carried out in aprotic or protic organicsolvents or mixtures thereof. Preference is given to alcohols, forexample methanol and ethanol, and aromatic hydro-carbons, for exampletoluene and xylene. The addition of co-solvents, for example ethers orcarboxylic acids, can speed up the reaction.

[0037] The reaction can be carried out at room temperature and also atelevated temperature; the preferred reaction temperature is from 60 to100° C.

[0038] The episulfide of formula IIIa can be isolated by separating offthe by-products by means of filtration, extraction, phase separation andsubsequent concentration by evaporating off the solvent.

[0039] It is also possible, however, for the episulfide of formula IIIato be further processed directly, in the form of the crude product insolution, without separating off the by-products.

[0040] The episulfide of formula IIIa is then dissolved in an aprotic orprotic organic solvent and, under inert gas (argon or nitrogen), reactedwith the amine R₅—NH—R₂, the amount of the amine preferably being soselected that there are from 1 to 10 NH groups for one episulfide group.Preferred solvents are alcohols (e.g. methanol, ethanol, tert-butanol)and aromatic hydrocarbons, for example toluene and xylene.

[0041] Preferably, the amine R₁—NH₂ is also used in the form of asolution in one of the above-mentioned organic solvents.

[0042] The reaction is advantageously carried out at elevatedtemperature, preferably at from 40° C. to 120° C.

[0043] The compounds of formula Ia according to the invention can beisolated by distilling off the solvent under reduced pressure. Theexcess amine R₅—NH—R₂ can then likewise be removed by distillation atelevated temperature. In a particular embodiment of the invention, theamine R₅—NH—R₂ is used as co-hardener, in which case separation of theproduct of formula Ia and the amine R₅—NH—R₂ is not necessary; rather,the reaction product can be used as a hardener for epoxy resins withoutfurther working-up. That procedure is recommended especially when usingdi- or poly-amines.

[0044] The present invention accordingly relates also to a process forthe preparation of compounds of formula Ia by reacting a compound offormula IIa

[0045] wherein A, X, R₁, R₃ and n are as defined hereinbefore,

[0046] with thiourea or a thiocyanate and subsequently reacting theresulting episulfide with an amine of formula R₅—NH—R₂ wherein R₅ and R₂are as defined hereinbefore.

[0047] The compounds of formula Ib can be prepared analogously from thecorresponding epoxy compounds of formula IIb.

[0048] The invention accordingly relates further to a process for thepreparation of compounds of formula Ib by reacting a compound of formulaIIb

[0049] wherein X, R₁, R₃ and R₅ are as defined hereinbefore, withthiourea or a thiocyanate and subsequently reacting the resultingepisulfide with a polyamine of formula E-(NHR₂)_(m+1) wherein E, R₂ andm are as defined hereinbefore.

[0050] Episulfides can, for example, also be synthesised from thecorresponding epoxides by reaction with triphenylphosphine sulfide.

[0051] In addition, episulfides can be prepared according toknown-methods directly from the corresponding alkenes, for example byreaction with m-chloroperbenzoic acid and subsequent reaction withthiourea in the presence of H₂SO₄, by reaction with propylene sulfide inthe presence of rhodium catalysts and also by reaction with(diethoxyphosphoryl)sulfenyl chloride, (diethoxythiophosphoryl)sulfenylbromide, thiobenzophenone S-oxide or bis(trimethylsilyl) sulfide.

[0052] As mentioned initially, the polymercaptopolyamines according tothe invention are especially suitable as hardeners for epoxy resins.

[0053] The invention relates further to a composition comprising

[0054] (A) an epoxy resin having, on average, more than one 1,2-epoxygroup per molecule, and

[0055] (B) a compound of formula Ia or Ib.

[0056] For preparation of the compositions according to the invention,the epoxy resins customary in epoxy resin technology are suitable ascomponent A. Examples of epoxy resins are:

[0057] I) polyglycidyl and poly(β-methylglycidyl) esters, obtainable byreacting a compound having at least two carboxyl groups in the moleculewith epichlorohydrin and β-methyl-epichlorohydrin, respectively. Thereaction is advantageously carried out in the presence of bases.

[0058] Aliphatic polycarboxylic acids may be used as the compound havingat least two carboxyl groups in the molecule. Examples of suchpolycarboxylic acids are oxalic acid, succinic acid, glutaric acid,adipic acid, pimelic acid, suberic acid, azelaic acid and dimerised ortrimerised linoleic acid.

[0059] However, cycloaliphatic polycarboxylic acids may also be used,for example tetrahydro-phthalic acid, 4-methyltetrahydrophthalic acid,hexahydrophthalic acid or 4-methylhexahydro-phthalic acid.

[0060] Aromatic polycarboxylic acids may also be used, for examplephthalic acid, isophthalic acid and terephthalic acid.

[0061] II) Polyglycidyl or poly(β-methylglycidyl) ethers, obtainable byreacting a compound having at least two free alcoholic hydroxy groupsand/or phenolic hydroxy groups with epichlorohydrin orβ-methylepichlorohydrin under alkaline conditions, or in the presence ofan acid catalyst and subsequently treating with an alkali.

[0062] The glycidyl ethers of this kind are derived, for example, fromacyclic alcohols, e.g. ethylene glycol, diethylene glycol and higherpoly(oxyethylene) glycols, propane-1,2-diol or poly(oxypropylene)glycols, propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene)glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol,glycerol, 1,1,1-trimethylol-propane, pentaerythritol, sorbitol and alsofrom polyepichlorohydrins.

[0063] Further glycidyl ethers of this kind are derived fromcycloaliphatic alcohols, e.g. 1,4-cyclo-hexanedimethanol,bis(4-hydroxycyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)-propane,or from alcohols that contain aromatic groups and/or further functionalgroups, e.g. N,N-bis(2-hydroxyethyl)aniline orp,p′-bis(2-hydroxyethylamino)diphenylmethane.

[0064] The glycidyl ethers can also be based on mononuclear phenols,such as resorcinol or hydroquinone, or on polynuclear phenols, such asbis(4-hydroxyphenyl)methane, 4,4′-dihydroxybiphenyl,bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane,2,2-bis(4-hydroxyphenyl)propane or2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane. Further hydroxy compoundsthat are suitable for the preparation of glycidyl ethers are novolaks,obtainable by condensing aldehydes, e.g. formaldehyde, acetaldehyde,chloral or furfuraldehyde, with phenols or bisphenols that areunsubstituted or substituted by chlorine atoms or by C₁-C₉alkyl groups,e.g. phenol, 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol.

[0065] III) Poly(N-glycidyl) compounds, obtainable bydehydrochlorination of the reaction products of epichlorohydrin withamines containing at least two amine hydrogen atoms. Such amines are,for example, aniline, n-butylamine, bis(4-aminophenyl)methane,m-xylylenediamine or bis(4-methylaminophenyl)methane.

[0066] The poly(N-glycidyl) compounds also include, however, triglycidylisocyanurate, N,N′-diglycidyl derivatives of cycloalkylene ureas, e.g.ethylene urea or 1,3-propylene urea, and diglycidyl derivatives ofhydantoins, e.g. 5,5-dimethylhydantoin.

[0067] IV) Poly(S-glycidyl) compounds, such as di-S-glycidyl derivativesderived from dithiols, e.g. ethane-1,2-dithiol orbis(4-mercaptomethylphenyl) ether.

[0068] V) Cycloaliphatic epoxy resins, e.g. bis(2,3-epoxycyclopentyl)ether, 2,3-epoxycyclo-pentylglycidyl ether,1,2-bis(2,3-epoxycyclopentyloxy)ethane or 3,4-epoxycyclohexylmethyl3′,4′-epoxycyclohexanecarboxylate.

[0069] It is also possible, however, to use epoxy resins wherein the1,2-epoxy groups are bound to different hetero atoms or functionalgroups; such compounds include, for example, the N,N,O-triglycidylderivative of 4-aminophenol, the glycidyl ether-glycidyl ester ofsalicylic acid,N-glycidyl-N′-(2-glycidyloxypropyl)-5,5-dimethylhydantoin and2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.

[0070] For preparation of the epoxy resin compositions according to theinvention, preference is given to the use of a liquid or solidpolyglycidyl ether or ester, especially a liquid or solid diglycidylether of bisphenol or a solid or liquid diglycidyl ester of acycloaliphatic or aromatic dicarboxylic acid, or a cycloaliphatic epoxyresin. Mixtures of epoxy resins can also be used.

[0071] Suitable solid polyglycidyl ethers and esters are compoundshaving melting points above room temperature up to about 250° C. Themelting points of the solid compounds are preferably in the range from50 to 150° C. Such solid compounds are known and, in some cases,commercially available. It is also possible to use, as solidpolyglycidyl ethers and esters, the advancement products obtained bypre-lengthening liquid polyglycidyl ethers and esters.

[0072] The epoxy resin compositions according to the invention compriseespecially a liquid polyglycidyl ether or ester.

[0073] Special preference is given, as component A, to diglycidyl ethersof bisphenol A, diglycidyl ethers of bisphenol F, mixtures of adiglycidyl ether of bisphenol A and a diglycidyl ether of bisphenol F,epoxy urethanes, aliphatic epoxy resins such as trimethylolpropanetriglycidyl ethers and also cycloaliphatic epoxy resins such ashexahydrophthalic acid diglycidyl ester.

[0074] The polymercaptopolyamines in accordance with the invention canadvantageously be used in combination with other epoxy hardeners,especially the customary amine hardeners.

[0075] The invention accordingly relates further to a compositioncomprising

[0076] (A) an epoxy resin,

[0077] (B) a compound of formula Ia or Ib and

[0078] (C) a polyamine.

[0079] Examples of suitable polyamines C are aliphatic, cycloaliphatic,aromatic and heterocyclic amines, for example bis(4-aminophenyl)methane,aniline-formaldehyde resins, benzylamine, n-octylamine,propane-1,3-diamine, 2,2-dimethyl-1,3-propanediamine(neopentanediamine), hexamethylenediamine, diethylenetriamine,bis(3-aminopropyl)amine, N,N-bis(3-amino-propyl)methylamine,triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine,2,2,4-trimethylhexane-1,6-diamine, m-xylylenediamine, 1,2- and1,4-diaminocyclohexane, bis(4-aminocyclohexyl)methane,bis(4-amino-3-methylcyclohexyl)methane,2,2-bis(4-aminocyclohexyl)propane and3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone-diamine),polyaminoimidazolines and polyaminoamides, for example those derivedfrom aliphatic polyamines and dimerised or trimerised fatty acids. Alsosuitable as amines (C) are the polyoxyalkyleneamines from Texaco knownas Jeffamines', for example Jeffamine' EDR148, D230, D400 and T403.

[0080] Further suitable polyamines (C) are1,14-diamino-4,11-dioxatetradecane, dipropylene-triamine,2-methyl-1,5-pentanediamine, N,N′-dicyclohexyl-1,6-hexanediamine,N,N′-dimethyl-1,3-diaminopropane, N,N′-diethyl-1,3-diaminopropane,N,N-dimethyl-1,3-diaminopropane, secondary polyoxypropylene-di- and-triamines, 2,5-diamino-2,5-dimethylhexane,bis(amino-methyl)tricyclopentadiene, m-aminobenzylamine,1,8-diamino-p-menthane, bis(4-amino-3,5-dimethylcyclohexyl)methane,1,3-bis(aminomethyl)cyclohexane, dipentylamine,bis(4-amino-3,5-diethylphenyl)methane, 3,5-diethyltoluene-2,4-diamineand 3,5-diethyltoluene-2,6-diamine.

[0081] As component A of the substance mixtures in accordance with theinvention, preference is given to cycloaliphatic and aliphatic amines,especially the amines of formulae R₅—NH—R₂ and E-(NHR₂)_(m+1) used forpreparation of the polymercaptopolyamines according to the invention.

[0082] The ratio of amounts of components A and B and, where applicable,C in the compositions according to the invention can vary within widelimits. The optimum ratio is dependent upon, inter alia, the kind ofamine, and can be readily determined by the person skilled in the art.

[0083] Component B and, where applicable, component C are preferablyused in amounts such that the sum of the amine and mercaptan equivalentsis from 0.5 to 2.0 equivalents, especially from 0.8 to 1.5 equivalents,and more especially from 0.9 to 1.2 equivalents, based on one epoxyequivalent.

[0084] The compositions according to the invention may optionallycomprise accelerators, for example tertiary amines or imidazoles.

[0085] Furthermore, the curable mixtures may comprise tougheners, forexample core/shell polymers or the elastomers or elastomer-containinggraft polymers known to the person skilled in the art as rubbertougheners.

[0086] Suitable tougheners are described, for example, in EP-A-449 776.

[0087] In addition, the curable mixtures may comprise fillers, forexample metal powder, wood flour, glass powder, glass beads, semi-metaland metal oxides, e.g. SiO₂ (Aerosils, quartz, quartz powder, fusedsilica powder), corundum and titanium oxide, semi-metal and metalnitrides, e.g. silicon nitride, boron nitride and aluminium nitride,semi-metal and metal carbides (SiC), metal carbonates (dolomite, chalk,CaCO₃), metal sulfates (barytes, gypsum), ground minerals and natural orsynthetic minerals chiefly of the silicate series, e.g. zeolites(especially molecular sieves), talcum, mica, kaolin, wollastonite,bentonite and others.

[0088] In addition to the additives mentioned above, the curablemixtures may also comprise further customary additives, e.g.antioxidants, light stabilisers, plasticisers, dyes, pigments,thixotropic agents, toughness improvers, antifoams, antistatics,lubricants and mould-release agents.

[0089] The curing of the epoxy resin compositions according to theinvention to form mouldings, coatings or the like is carried out in amanner customary in epoxy resin technology, for example as described in“Handbook of Epoxy Resins”, 1967, by H. Lee and K. Neville.

[0090] Special mention should be made of the high reactivity of thepolymercaptopolyamines according to the invention with respect to epoxyresins even at low temperatures (from −5° C. to 25° C.).

[0091] The curable mixtures exhibit only a slight tendency tocarbonatisation (becoming cloudy). The cured products are distinguishedby surprisingly high resistance to chemicals and resistance toweathering.

[0092] The invention relates further to the cross-linked productsobtainable by curing a composition according to the invention.

[0093] The compositions according to the invention are excellentlysuitable as a coating composition, adhesive, bonding composition forcomposite materials or casting resin for the manufacture of mouldings.

EXAMPLES I. Preparation of Compounds of Formula I

[0094] a) General procedure for the preparation of polyepisulfides:

[0095] The polyepoxide of formula II is dissolved in an amount ofsolvent that is from 0.5 to 5 times the amount of the polyepoxide and isstirred, under nitrogen, with thiourea or alkali-metal or ammoniumthiocyanate (0.8-1.2 equivalents of sulfur per epoxy equivalent) at60-100° C. until the epoxy content has fallen to nearly zero.

[0096] After separating off the by-products by means of filtration,extraction or phase separation, the polyepisulfide is isolated as aresult of concentration by evaporating off the solvent.

[0097] b) General procedure for the preparation ofpolymercaptopolyamines:

[0098] The polyepisulfide is dissolved in an amount of solvent that isfrom 0.5 to 5 times the amount of the polyepisulfide and, under nitrogenand with vigorous stirring, is combined with the amine, which likewisehas been dissolved in an amount of solvent that is from 0.5 to 5 timesthe amount of the amine. The amount of amine is selected so that thereare from 1 to 10 NH₂ groups for one episulfide group. After stirring at60-100° C. for from 0.2 to 3 hours, the solvent is distilled off underreduced pressure. To isolate the polymercapto-polyamine of formula I,the excess amine reagent is removed by means of vacuum distillation atelevated temperature.

[0099] In one embodiment of the invention, the excess amine is notremoved and the mixture of the amine R₁—NH₂ and thepolymercaptopolyamine of formula I is used as hardener for epoxy resins.

[0100] In accordance with the above-mentioned procedure,polymercaptopolyamines according to the invention (Examples I.1-I.19)are prepared from the following diamines R₁—NH₂ and epoxides of formulaII:

[0101] BA: n-butylamine

[0102] OA: n-octylamine

[0103] CYA: cyclohexylamine

[0104] BZA: benzylamine

[0105] MBA: methylbutylamine

[0106] DMDP: N,N-dimethyl-1,3-diaminopropane

[0107] MDP: N-methyl-1,3-diaminopropane

[0108] DACY: 1,2-diaminocyclohexane

[0109] AEP: N-2-aminoethylpiperazine

[0110] DETA: diethylenetriamine

[0111] IPD: isophoronediamine

[0112] MXDA: meta-xylylenediamine

[0113] DYTEK-A: 1,5-diamino-2-methylpentane

[0114] NBDA: isomeric mixture of 2,5- and 2,6-bis(aminomethyl)norbornane

[0115] EDA: ethylenediamine

[0116] epoxide 1: liquid diglycidyl ether of bisphenol A having an epoxycontent of 5.25-5.4 eq./kg

[0117] epoxide 2: liquid mixture of diglycidyl ether of bisphenol A anddiglycidyl ether of bisphenol F having an epoxy content of 5.5-5.8eq./kg

[0118] epoxide 3: 1,4-bis(hydroxymethyl)cyclohexane diglycidyl ether

[0119] epoxide 4: epoxy phenol novolak having an epoxy content of5.6-5.8 eq./kg

[0120] epoxide 5: diglycidyl ether of hydrogenated bisphenol A

[0121] epoxide 6: tetraglycidyl ether of formula

[0122] epoxide 7: di(β-methylglycidyl) ether of bisphenol A

[0123] epoxide 8: trimethylolpropane triglycidyl ether

[0124] epoxide 9: hexahydrophthalic acid diglycidyl ester (epoxycontent: 5.6-6.2 eq./kg)

[0125] epoxide 10: phenyl glycidyl ether

[0126] The reaction conditions and the properties of the final productsare listed in Table 1. TABLE 1 molar ratio Starting products episulfide/viscosity amine value Example amine epoxide amine T/° C. [mPa · s][equivalents/kg] I.1 DETA epoxide 1 1:5 100     1900*⁾ 10.5 I.2 DETAepoxide 1 1:5 100  >50 000 7.1 I.3 IPD epoxide 1 1:5 100     5300*⁾ 7.6I.4 MXDA epoxide 1 1:5 60     2030*⁾ 9.6 I.5 MXDA epoxide 1 1:5 60  >50000 — I.6 MXDA epoxide 1 1:4 60     9000*⁾ 8.5 I.7 MXDA epoxide 2 1:5 55    2200*⁾ 9.2 I.8 MXDA epoxide 2 1:4 55     4400*⁾ 8.1 I.9 MXDA epoxide2 1:3 55    50 000*⁾ 7.6 I.10 IPD epoxide 2 1:5 100    27 000*⁾ 7.8 I.11IPD epoxide 2 1:3 100  >50 000*⁾ 6.3 I.12 DETA epoxide 2 1:5 100    2000*⁾ — I.13 DYTEK-A epoxide 2 1:5 100     1600*⁾ 10.0 I.14 NBDAepoxide 2 1:5 60    13 500*⁾ 8.4 I.15 EDA epoxide 2 1:5 100  >50 000 —I.16 MXDA epoxide 3 1:5 60      300*⁾ 9.8 I.17 MXDA epoxide 3 1:4 60     500*⁾ 8.8 I.18 IPD epoxide 3 1:4 60      970*⁾ — I.19 DETA epoxide3 1:5 100  >50 000 — I.20 BA epoxide 2 1:10 77  >60 000 2.6 I.21 CYAepoxide 2 1:10 100  >60 000 3.3 I.22 BZA epoxide 2 1:10 100  >60 000 2.8I.23 OA epoxide 2 1:10 90  >60 000 I.24 CYA epoxide 4 1:10 100  >60 0004.1 I.25 BZA epoxide 4 1:10 100  >60 000 3.6 I.26 BA epoxide 3 1:10 803000-7000 2.9 I.27 CYA epoxide 3 1:10 100  >60 000 3.1 I.28 BZA epoxide3 1:10 100    10 200 3.0 I.29 OA epoxide 3 1:10 100 I.30 BA epoxide 51:10 75 >128 000 2.15 I.31 MBA epoxide 5 1:10 75    13 440 — I.32 BAepoxide 6 1:20 75 >128 000**⁾ 2.04 I.33 MBA epoxide 6 1:20 60    12 800— I.34 IPD epoxide 6 1:20 60 >128 000**⁾ 7.83 I.35 DMDP epoxide 3 1:1070     1400 7.42 I.36 MDP epoxide 3 1:10 65    43 520 6.17 I.37 DACYepoxide 3 1:5 65      840 10.71 I.38 AEP epoxide 3 1:5 65      400 10.45I.39 MBA epoxide 3 1:2 67     1040 — I.40 BA epoxide 7 1:10 70 >128 0003.10 I.41 DACY epoxide 3 1:2 75    87 040 6.34 I.42 AEP epoxide 3 1:2 77   11 520 6.72 I.43 MBA epoxide 6 1:15 80     1160 — I.44 MBA epoxide 81:3 70 >128 000 — I.45 IPD epoxide 2:1 75 >128 000 2.83 10 I.46 BAepoxide 1:5 78     3040 2.75 10

Application Examples

[0127] II.1 Polymercaptopolyamine as Hardener for Epoxy Resins

[0128] 100 g of a liquid diglycidyl ether of bisphenol A having an epoxycontent of 5.25-5.4 eq./kg are mixed with 28 g of thepolymercaptopolyamine of Example I.4 at 20° C. The mixture is applied toglass plates or steel plates using a doctor blade (thickness of layer:0.2 mm) and fully cured for 10 days at 20° C.

[0129] For comparison purposes, 100 g of the same epoxy resin are fullycured using 20 g of a commercially available amine hardener (DETA) underthe same conditions.

[0130] The fully cured coatings exhibit the properties listed in Table2. TABLE 2 according to the invention comparison Example II.1(polymercaptopolyamine) (DETA) viscosity (DIN 53018 T1/76) 5600 8650[mPa · s] gel time according to TECAM at 20° C.[min] 35 15 dust-dry time[h] at 20° C. 2.0 >30 at 5° C. 2.5 >30 exudation at 5° C. noneconsiderable hardness according to Persoz (ISO 1552) [s] at 20° C. after1 day 358 340 after 1 week 383 365 after 1 month 394 355 hardnessaccording to Persoz (ISO 1552) [s] at 5° C. after 1 day 235 80 after 1week 267 220 after 1 month 386 250

[0131] II.2 Polymercaptopolyamine as Co-hardener in Admixture with OtherPolyamine Hardeners

[0132] 100 g of a liquid diglycidyl ether of bisphenol A having an epoxycontent of 5.25-5.4 eq./kg are mixed with 17 g of a commerciallyavailable amine hardener (DETA) and 4.2 g of the polymercaptopolyamineof Example I.5. The mixture is processed and fully cured as described inExample II.1.

[0133] For comparison purposes, the above-mentioned mixture without theaddition of the polymercaptopolyamine is fully cured under the sameconditions.

[0134] The fully cured coatings exhibit the properties listed in Table3. TABLE 3 according to the invention (polymercaptopolyamine +comparison Example II.2 DETA) (DETA) gel time according to TECAM 19 15at 20° C. [min] dust-dry time [h] at 20° C./ 4 >30 65% rel. humidityfull hardening time [h] at 13 >30 20° C./65% rel. humidity hardnessaccording to Persoz (ISO 1552) [s] after 1 d at 20° C. 310 195 after 7 dat 20° C. 349 229 after 1 d at 5° C.  73 (tacky) 24 (tacky) after 7 d at5° C. 148 (tacky) 39 (tacky)

[0135] II.3 Polymercaptopolyamine as Hardener for Epoxy Resins

[0136] The polymercaptopolyamine prepared according to Example I.26 ismixed with the epoxy resins and further additives listed in Table 4 andfully cured.

[0137] The properties of the mixtures and of the cured products arelikewise listed in Table 4. TABLE 4 Example II.3.1 II.3.2 II.3.3 epoxide9 [g]      41 epoxide 8 [g]      37.4 epoxide 6 [g]      43.32polymercaptopolyamine [g]      29      32.6      26.68 TiO₂ (Kronos2310) [g]      30      30      30 flow improver BYK 300 [g]       0.14      0.14      0.14 methyl ethyl ketone [g]      8.8 viscosity(Epprecht viscosimeter) at 20° C. of freshly prepared mixture     5760    3520     2720 [mPa · s] after 60 min [mPa · s] >128 000 >128 000  76 800 curing for 12 days at RT hardness according to Persoz      20     24      63 [s] impact deformation¹⁾ (direct    >160    >30     >60impact) [cm · kg] impact deformation (reverse    >80    >20    >20impact) [cm · kg] Erichsen indentation test²⁾      10.5       8.9     9.3 [mm] acetone test       2       2 1-2 curing for 30 min at 80°C. and 12 d at RT hardness according to Persoz      20      26     113[s] impact deformation¹⁾ (direct    >160    >30    >60 impact) [cm · kg]impact deformation (reverse    >80    >10    >30 impact) [cm · kg]Erichsen indentation test²⁾      10.6       9.1      9.8 [mm] acetonetest³⁾       2       2      1

1. A compound of formula Ia or Ib,

wherein A is an (n+1)-valent aliphatic, cycloaliphatic, araliphatic oraromatic radical and n is an integer from 0 to 5, E is an (m+1)-valentaliphatic, cycloaliphatic, araliphatic or aromatic radical and m is aninteger from 0 to 3, X is —O—, —COO— or —CHR₄—, with R₄ and R₃ togetherforming an ethylene group, R₁ and R₂ are, each independently of theother, hydrogen or methyl, R₃ is hydrogen, or R₃ and R₄ together form anethylene group, and R₅ is a monovalent aliphatic, cycloaliphatic,araliphatic or aromatic radical.
 2. A compound of formula Ia accordingto claim 1, wherein X is —O— and A is a bivalent radical of a bisphenolor of a cycloaliphatic diol, the radical of a phenol novolak or cresolnovolak, the bi- to tetra-valent radical of an isocyanate/polyol adductor the tri- to hexa-valent radical of a tri- to hexa-functionalaliphatic polyol.
 3. A compound of formula Ia according to claim 1,wherein X is —O— and A is a bivalent radical of formula

the radical of a phenol novolak or cresol novolak, a trivalent radicalof formula

or

or the tetravalent radical of formula


4. A compound of formula Ia or Ib according to claim 1, wherein R₅ isC₁-C₂₀alkyl, C₅-C₁₂-cycloalkyl, C₆-C₁₀aryl or C₇-C₁₂aralkyl, each ofwhich is unsubstituted or substituted by one or more amino groups,hydroxyl groups, C₁-C₈alkoxy groups or halogen atoms.
 5. A compound offormula Ia or Ib according to claim 1, wherein R₅ is C₂-C₁₀alkyl,C₂-C₁₀aminoalkyl, phenyl, benzyl, cyclohexyl or a radical of formulaH₂N—Z—CH₂—NH—, wherein Z is a bivalent cycloaliphatic, araliphatic oraromatic radical or a radical of formula —(CH₂CH₂NH)_(k)—CH₂—, wherein kis 2 or
 3. 6. A compound of formula Ia or Ib according to claim 1,wherein R₁ is n-butyl, n-octyl, cyclohexyl, benzyl, 2-aminoethyl,4-(aminomethyl)pentyl, 5-amino-2-methylpentyl, 3-dimethylaminopropyl,3-methylaminopropyl, 4-aminocyclohexyl or a radical of formula—CH₂CH₂NHCH₂CH₂NH₂,


7. A compound of formula Ia or Ib according to claim 1, wherein X is O—and R₁ and R₃ are hydrogen.
 8. A process for the preparation of acompound of formula Ia according to claim 1 by reacting a compound offormula IIa

wherein A, X, R₁, R₃ and n are as defined in claim 1, with thiourea or athiocyanate and subsequently reacting the resulting episulfide with anamine of formula R₅—NH—R₂ wherein R₅ and R₂ are as defined in claim 1.9. A process for the preparation of a compound of formula Ib accordingto claim 1 by reacting a compound of formula IIb

wherein X, R₁, R₃ and R₅ are as defined in claim 1, with thiourea or athiocyanate and subsequently reacting the resulting episulfide with apolyamine of formula E-(NHR₂)_(m+1) wherein E, R₂ and m are as definedin claim
 1. 10. A composition comprising (A) an epoxy resin and (B) acompound of formula Ia or Ib according to claim
 1. 11. A compositionaccording to claim 10 comprising, in addition, (C) a polyamine.
 12. Acomposition according to either claim 10 or claim 11 comprisingcomponent B and, where applicable, component C in such amounts that thesum of the amine and mercaptan equivalents is from 0.5 to 2.0equivalents, based on one epoxy equivalent.
 13. A cross-linked productobtainable by curing a composition according to claim
 10. 14. Use of acomposition according to claim 10 as coating composition, adhesive,bonding composition for composite materials or casting resin for themanufacture of mouldings.